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DELETE Deletes KSAM files or data set entries. DELETE cannot be used with MPE files. Syntax DELETE[(modifier)] file-name[,option-list]; DELETE specifies the deletion of one or more KSAM file entries or data set entries. For multiple deletions, the entries to be deleted are determined by match criteria specified in the match register. If you do not specify match criteria for a multiple deletion, DELETE deletes all entries in a chain or in the entire file or data set, depending on the modifier. If you are performing dynamic transactions (Transact/iX only), be aware that transactions have a length limit. For a discussion about how DELETE is affected by this limitation, see "Limitations" under "Dynamic Roll-back" in Chapter 6.
NOTE After the first retrieval, Transact uses an asterisk (*) for the call list to optimize subsequent retrievals of that data set.
Statement Parts modifier To specify type of access to the KSAM file or data set, choose one of the following modifiers: none Deletes an entry from a master set based on the key value in the argument register; this option does not use the match register. CHAIN Deletes entries from a detail set or a KSAM chain. The entries must meet any match criteria set up in the match register. The contents of the key and argument registers specify the chain in which the deletion is to occur. If no match criteria are specified, all entries are deleted. If match criteria is used, all items specified in the match register must be included in a LIST= option. CURRENT Deletes the last entry that was accessed from the KSAM file or data set. DIRECT Deletes the entry stored at the specified record number in a KSAM file, a detail set, or a master set. Before using this modifier, you must store the record number as a 32-bit integer in the item specified by the RECNO= option. PRIMARY Deletes the master set entry stored at the primary address of a synonym chain. The primary address is located through the key value in the argument register. ____________________________________________ NOTE DELETE(PRIMARY) deletes only one entry at the primary location, and the secondary entry, if any, automatically migrates to the primary location after the delete. ____________________________________________ RCHAIN Deletes entries from a detail set or a KSAM chain in the same manner as the CHAIN option, only in reverse order. For a KSAM file, this operation is identical to CHAIN. RSERIAL Deletes entries from a data set in the same manner as the SERIAL option, except in reverse order. For a KSAM file, this operation is identical to SERIAL. SERIAL Deletes entries in serial mode from a KSAM file or from a data set that meet any match criteria set up in the match register. If no match criteria are specified, all entries are deleted. If match criteria are specified, the match items must be included in a LIST= option. file-name The KSAM file or data set to be accessed in the deletion. If the data set is not in the home base as defined in the SYSTEM statement, the base name must be specified in parentheses as follows: set-name(base-name) option-list One or more of the following options, separated by commas: ERROR=label Suppresses the default error return that [([item-name])] Transact normally takes. Instead, the program branches to the statement identified by label, and the stack pointer for the list register is set to the data item item-name. Transact generates an error at execution time if the item cannot be found in the list register. The item-name must be a parent. If you omit item-name, as in ERROR = label();, the list register is cleared. If you use an "*" instead of item-name, as in ERROR = label(*);, then the list register is not touched. LIST=(range- The list of items from the list register list) to be used for the DELETE operation. For data sets, no child items can be specified in the range list. If the LIST= option is omitted with any modifier, all the items named in the list register are used. When the LIST= option is used, only the items specified in a LIST= option have their match conditions applied when the items are included in the match register. When the LIST= option is omitted, items which appear in the list register and the match register have their match conditions applied. Otherwise, the match conditions for an item are ignored. The match register can be used only with the modifiers CHAIN, RCHAIN, SERIAL, or RSERIAL. Each retrieved entry is placed in the area of the data register indicated by LIST= before any PERFORM= is executed, and then the delete is performed. For all options of range-list, the data items selected are the result of scanning the data items in the list register from top to bottom, where top is the most recent entry added to the list register. (See Chapter 4 for more information on registers.) The LIST= option has a limit of 64 individually listed item names and a limit of 255 items specified by a range for a TurboIMAGE data set. All item names specified must be parent items. The options for range-list and the data items they cause DELETE to access include the following: (item-name) A single data item. (item-nameX: All the data items in the item-nameY) range from item-nameX through item-nameY. In other words, the list register is scanned for the occurrence of item-nameY closest to the top of the list register. From that entry, the list register is scanned for item-nameX. All data items between are selected. An error is returned if item-nameX is between item-nameY and the top of the list register. Duplicate data items can be included or excluded from the range, depending on their position on the list register. For example, if range-list is A:D and the list register is as shown,then data items A, B, C, D, and D are selected. For database files, an error is returned if duplicate entries are selected. If item-nameX and item-nameY are marker items (see the DEFINE(ITEM) verb) and if there are no data items between the two on the list register, no database access is performed. (item- All data items in the range nameX:) from the last entry through the occurrence of item-nameX closest to the top of the list register. (:item- All data items in the range nameY) from the occurrence of item-nameY closest to the top through the bottom of the list register. (item-nameX, The data items are selected item-nameY, from the list register. For ... databases, data items can be item-nameZ) specified in any order. For KSAM files, data items must be specified in the order of their occurrence in the physical record. This order need not match the order of the data items on the list register. This option is less efficient to use than the options listed above. (@) Specifies a range of all data items of file-name as defined in the data dictionary. The range-list is defined as item-name1:item-namen for the file. (#) Specifies an enumeration of all data items of file-name as defined in the data dictionary. The data items are specified in the order of their occurrence in the physical record or form as defined in the dictionary. This order need not match the order of the data items in the list register. ( ) A null data item list. That is, delete the entry or entries, but do not retrieve any data. LOCK Locks the specified file or database. If a data set is being accessed, the lock is set the whole time that DELETE executes. If LOCK is not specified but the database is opened in mode 1, which requires a lock, the lock specified by the type of automatic locking in effect is active while the entry is processed by any PERFORM= statements, but is unlocked briefly before the next entry is retrieved. For a KSAM file, if LOCK is not specified on DELETE but is specified for the file in the SYSTEM statement, then the file is locked before each entry is retrieved, remains locked while the entry is processed by any PERFORM= statements, but is unlocked briefly before the next entry is retrieved. (DELETE is not allowed on MPE files.) Including the LOCK option overrides SET(OPTION) NOLOCK for the execution of the DELETE verb. A database opened in mode 1 must be locked while DELETE executes. For transaction locking, you can use the LOCK option on the LOGTRAN verb instead of the LOCK option on DELETE if SET(OPTION) NOLOCK is specified. If a lock is not specified (for a database opened in mode 1) an error is returned. See "Database and File Locking" in Chapter 6 for more information. NOCOUNT Suppresses the message normally generated to indicate the number of deleted entries. NOMATCH Ignores any match criteria set up in the match register. NOMSG Suppresses the standard error message produced as a result of a file or database error. PERFORM=label Executes the code following the specified label for every entry retrieved by the DELETE verb before the DELETE operation. The entries can be optionally selected by match criteria. This option allows operations to be performed on retrieved entries without having to code loop-control logic. You can nest up to a maximum of ten PERFORM options. RECNO=item-name With the DIRECT modifier, you must define [(subscript)] item-name to contain the 32-bit integer number (I(9,,4)) of the record to be deleted. With other modifiers, Transact returns the record number of the deleted record in the 32-bit integer item-name. The item-name can be modified with subscript if the referenced item is an array item. (See "Array Subscripting" in Chapter 3.) SINGLE Deletes only the first selected entry. SOPT Suppresses the optimization of database calls. This option is primarily intended to support a database operation in a performed routine that is called recursively. The option allows a different path for the same detail set to be used at each recursive entry, rather than optimizing to the same path. It also suppresses generation of a call list of "*" after the first call is made. Use SOPT if you are calling TurboIMAGE through the PROC or CALL verbs. For an example of how SOPT is used, see "Examples" at the end of the FIND verb description. STATUS Suppresses the actions defined in Chapter 7 under "Automatic Error Handling." You may want to add status checking to your code if you use this option. When STATUS is specified, the effect of a DELETE statement is described by the 32-bit integer value in the status register: Status Meaning Register Value 0 The DELETE operation was successful. -1 A KSAM or MPE end-of-file condition occurred. >0 For a description of the condition that occurred, refer to database or MPE/KSAM file system error documentation corresponding to the value. STATUS causes the following with DELETE: * Normal multiple accesses/deletions become single. * The normal rewind done by the DELETE is suppressed, so CLOSE should be used before DELETE(SERIAL) or DELETE(RSERIAL). * The normal find of the chain head by the DELETE is suppressed, so PATH should be used before DELETE(CHAIN) or DELETE(RCHAIN). See "Using the STATUS Option" in Chapter 7. Examples In the following example, the programmer wants to be sure that an entry is not in MASTER-SET. Therefore, there are two acceptable conditions: either a status register value of zero (delete successful) or a status register value of 17 (database error 17--record not found) is acceptable. DELETE MASTER-SET, LIST=(KEY-ITEM), STATUS; IF STATUS = 17,0 THEN DISPLAY "ENTRY REMOVED" ELSE DO DISPLAY "ERROR ON DELETE FROM MASTER-SET"; GO TO ERROR-CLEANUP; DOEND; This example deletes all entries that contain a DEBT-LEVEL less than the number entered by the user. DEBT-LEVEL is required in the LIST= option because DELETE reads each record in the chain into the data register area associated with DEBT-LEVEL in order to check the match criteria before deleting the entry. PROMPT(MATCH) DEBT-LEVEL,LT; DELETE(CHAIN) DEBT-DETL, LIST=(DEBT-LEVEL); This example deletes only the last entry in the data set that matches the zip code entered by the user. PROMPT(MATCH) ZIP ("DELETE ZIP CODE"); DELETE(RSERIAL) DETAIL-SET, SINGLE, LIST=(NAME:ZIP), PERFORM=LISTIT;
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